Programmatic subscription with minimal API not working as expected with raw messages

[rochabr]

Expected Behavior

In theory, programmatically mapping a subscription route should work like the following:

// Map the route for both HTTP and Dapr
app.MapPost("/messages", handler)
   .WithTopic("redis-pubsub", "employeemessage", true)  // This enables Dapr subscription - true == raw messages
   .WithName("ProcessMessage")
   .WithTags("Messages")
   .WithOpenApi();

Actual Behavior

However in this case, the subscriber is not able to parse the message as it is expecting an octet-stream.

The code above returns:

== APP == info: Subscriber.API.Modules.MessagesModule[0]
== APP ==       {"data_base64":"eyJpZCI6MiwibmFtZSI6IkphbmUgRG9lIn0=","datacontenttype":"application/octet-stream","id":"f5f38e3a-f07d-4d57-8699-535e80e62fd6","pubsubname":"redis-pubsub","source":"Dapr","specversion":"1.0","topic":"employeemessage","type":"com.dapr.event.sent"}

Steps to Reproduce the Problem

Follow the instructions here: https://github.com/rochabr/mediatr-dapr-sample and make the necessary changes within MessageModule.cs and Program.cs In the Subscriber.API project.

To bypass the issue, I had to map the subscription endpoint explicitly:

//Dapr subscription endpoint - using absolute path to avoid conflicts
app.MapGet("/dapr/subscribe", (HttpContext context) =>
{
    var subscriptions = new[]
    {
        new
        {
            pubsubname = "redis-pubsub",
            topic = "employeemessage",
            route = "/messages",
            metadata = new Dictionary<string, string>
            {
                { "isRawPayload", "true" },
                { "content-type", "application/json" }
            }
        }
    };
    return Results.Ok(subscriptions);
})
.ExcludeFromDescription();  // This excludes it from OpenAPI/Swagger


//Message handler endpoint
app.MapPost("/messages", employeeHandler)
   .WithTags("Messages");